Natural gas storage via clathrate hydrate formation: Effect of carbon dioxide and experimental conditions

Abstract

The increasing demand on natural gas poses a great need for the development of efficient and effective gas storage and transport technologies. Clathrate hydrate formation is one possible option which stores gas in the solid form (solidified natural gas, SNG). CO2 is one major contaminant in natural gas. In this work, we examined the kinetic performance of CO2/CH4 hydrate formation in presence of tetrahydrofuran (THF). 24% CO2/76% CH4 was employed to simulate the natural gas. Hydrate formation was compared between CH4/THF and CO2/CH4/THF systems at 283.2 K and 3.0 MPa. With 24% CO2 in feed gas, the hydrate formation rate was significantly decreased. However, the final amount of CH4 stored in hydrates did not drop much. Furthermore, hydrate formation kinetics was enhanced remarkably by increasing the experimental pressure to 7.0 MPa. However, when the temperature was increased to 293.2 K, the hydrate formation exhibited a fairly low gas consumption rate and a much longer time to complete the process. Overall, the small loss of CH4 storage capacity shows the possibility to directly store and transport CO2 contaminated natural gas in hydrates without pre-separation, however, challenge is still there to improve the hydrate formation kinetics.